The flow properties of aqueous slurries containing salicylic acid, sodium salicylate and gum arabic, prepared as feed-liquids into spray drying chamber, were investigated by analysis of their flow curves obtained using a cone and plate viscometer. Their flow curves showed a thixotropy, having two Newtonian flow curves at low and high shear rates and a characteristic spur-like protrusion between two Newtonian flow curves. Spur in their curves is thought to result from a sharp breakdown point in the card-house structure in slurry at the movement of salicylic acid particles. Apparent viscosity of the first Newtonian flow (η_N1) at the low shear rate was larger than that (η_N2) of the second Newtonian flow and was related to sedimentation volume of salicylic acid only. The second Newtonian apparent viscosity was related to concentrations of gum arabic and sodium salicylate, and active energy for it was 3-12kcal/mol. When geometric mean diameters of salicylic acid particles in slurries were large, or geometric standard deviations of distributions or shape factors of them were small, thixotropy coefficients (η_R=η_N1/η_N2) were large and represented resistance for movement of solid particles in slurries to be large at the low rate of shear. When the distribution of solid particles were broad and shape factor of them were large, small and narrow particles act as glidants or rollers to facilitate the rotation of larger particles resulting in the reduction of the thixotropy of slurry.

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An application of the theory of stochastic processes to the single particle crushing of brittle materials was examined by using two kinds of glassy materials and six kinds of minerals. From the experiments, the following results were obtained. 1) In sphere compression tests under constant loading rate (0.3ton/min), the relations of the probability of fracture per unit time λ and the fracture load f were expressed by the following equation: λ=Aexp(α⋅f) where α is an index. The value of α increased with the decrease of hardness of materials. 2) In sphere compression tests, α obtained by wet crushing were larger than that obtained by dry crushing. 3) In both the spherical specimen and the cylindrical specimen, in spite of various loading rates, the relation between α and f was expressed by the above equation, and each of tests had a constant value of α. 4) From the value of λ, we could calculate the frequency distributions of the time required for completion of the fracture.

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An experimental equation has been presented for the compression of dry powdered materials. Although various equations for powder compression have been presented by many investigators, none of these equations are fully representing the relation between the applied pressure and the bulk density of the powder for a wide range of the pressure.
The authors have carried out an experimental work on the powder compression for a wide range of the pressure (1 to 1600kg/cm²) using the powders of alumina, calcium carbonate and fly ash. Using the data obtained, several existing equations are checked and have found that among these equations Kawakita's equation is the most useful one. A newly proposed equation by the authors has been shown to be applicable to more wide range of the pressure than the former equations. Also this equation is convenient for the practical use because it does not include the state of initial packing which is affected by the method of filling.

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